Nudge by frame broken in Cubase 9

“Nudge -1 Frame” and “Nudge +1 frame” behaves incorrectly in Cubase 9 but works fine in Cubase 8 with the same video file. In Cubase 9, doing this often causes Cubase to display a random frame from elsewhere in the video. In Cubase 8 the nudging displays the frames correctly. I’m using a ProRes file like recommended.